Tag Archives: oil cooler mount

I mentioned in the last post that after getting the wheel pants on Betty, the airplane was ALMOST ready to fly. The reason it wasn’t fully ready was during the wheel pant installation I removed the cowl. When I removed the cowl, I found this floating around inside the bottom cowl.

When I initially found it, I couldn’t figure out where it was from. So I set it aside, and knew that I was going to have to figure out where it was from. After thinking about it on and off for a few days, the type of aluminum and shape reminded me of the oil cooler attach flanges. Sure enough, the forward upper oil cooler flange had cracked through.

It certainly didn’t do all of that in the last flight. So this problem serves as a reminder to spend more time and be more thorough inspecting. With the forward flange cracked, the oil cooler found a new “home.” The new place the oil cooler wanted to be was about 1/8″ off the top forward mounting location. This said to us that there was some slight misalignment in the mounting bracketry for the oil cooler. This placed the flanges under pre-load. The flanges are very soft aluminum and when under pre-load are prone to cracking.

After consulting with Greg, Pacific Oil Coolers, and a few other folks, the plan for the fix was to eliminate the pre-load and also to add cross tube supports between then flanges of the oil cooler. These cross tubes make each pair of flanges a unit and will prevent the flanges from “working” under vibration and engine operation. To eliminate the pre-load we added a spacer in the mounting brackets that took up the 1/8″ gap. The spacer is made out of baffle seal material (silicone) and has some give. Hopefully this will also provide some vibration isolation.

With Oshkosh coming up quickly, I decided to buy a new oil cooler to expedite Betty’s return to the air. Then I would send in the broken one and have Pacific Oil Coolers repair the flange. This way I have a spare, and if the fix proves successful, I can either use the repaired oil cooler on my next airplane, or sell it. Then again, having spare parts is always nice too… I have to note that Wayne at Pacific Oil Cooler really treated me well for all of this. After all, the problem was my fault, but they went out of their way. Terrific customer service.

The oil cooler installation will be a watch item over now. It will require more frequent inspection to verify that we have appropriately fixed the misalignment and that the flanges are no longer prone to cracking.

One of the cool things about blogging about this project is that I have quite a few builders following. Builders who are still building, and builders who are flying. It is always nice to have those people watching over what you are doing and giving you tips, suggestions, and keeping you motivated. One of those people, James Redmon, who has built an award winning Berkut (and also finished a second one, and is working on a third one), sent me a note suggesting a few things I should do in response to yesterday’s post. One thing was add strain relief on the oil temperature probe by adding a dab of shoe goo to the end of it as they are known to break wires easily. The second is to use a more modern hose for the oil cooler installation. Both of which will be done, and you will see them as they get done. Thanks a ton James!

Alright, on to today. This morning I started by adding aluminum grommets to the wire pass throughs in the firewall. To do this you use versatube, which is dead soft aluminum tubing. It is actually a simple process, but required making a few ‘extra’ parts to get it right. You start by cutting a oversized length of aluminum tube to work with. I made a tubing clamp for the vice by drilling a 5/8″ hole in a block of 2×4, then cut it across the center of the hole. This allows you to rigidly hold the tube to form a flange on one end.

Then you start to make the flange. I started by putting a bullet shape on a piece of aluminum rod and using that as a lever to start to flare out the tube. I noticed that this was deforming the interior of the tube, putting dimples in it. That wouldn’t do, so I started again. This time I used a piece of wooden dowel with the same bullet shape to start the flare. This worked well and didn’t dimple the inside. I was only able to get about the first 25-30 degrees of the flange done this way. Then I switched to using a hammer with the dowel to get the flange to bend further. As I was getting closer to having the flange, I used a plastic ended mallet and finished the flange. Once there is a flange, I took it over to the bench grinder and polished the flange.

Then you insert the tube into the hole in the firewall and mark the thickness of the straight section for the grommet. Then I added 1/4 inch to the length and cut it off. Then for the fun part. You put it in the firewall and hold a bucking bar against the flange. This requires two people, or someone much stronger than me. Luckily for me, Greg was here all day. With the bucking bar holding the flange flush against the forward side of the firewall, we started with the dowel to start a flange. It is hard to use the dowel with a short grommet like this. But we got a start. Then we took the rounded side of my ball-peen hammer (which happened to be the perfect diameter) and held that against started flange centered on the tube. We used a second hammer to strike the ball-peen all while holding the bucking bar firm against the forward flange. This produced great results. We stopped using the ball-peen when we were 80 percent of the way done.

Then we switched to a sledge hammer. I know what your thinking. But we held that in place of the ball-peen and struck that with another hammer. The advantage to doing this was we had a flat surface on both side of the sledge and we weren’t risking putting a dent in the stainless steel firewall. This got the grommet 99% of the way there. A few taps with a rubber mallet and the edges sat down beautifully. It was fun to see it work so well. I am happy with the result. Here is the first one, on the right side of the firewall.

And the one on the left side.

I have to admit, I cannot take credit for this idea. It was stolen from James Redmon’s Berkut 13 site. I highly recommend it. It works well and makes a very professional looking grommet. The edges are very smooth and there will not be any wire chafing. Once all the wires are run, the hole will be sealed with RTV.

After this was all done, I spent some time in the hell hole. It is not fun working in there, over your head, in a confined space. Who in the heck decided to mount so much crap in there? I guess I have to blame the builder…. Anyways. I started by putting final hardware on the autopilot roll servo mount and linkages to the roll torque tube. It was a tedious task. As I said, there isn’t much room in there, and the throw you can get with a ratchet is pitiful.But the servo is rigidly mounted, and all the final hardware for the aileron torque tube is in place, and torqued down.

The most difficult part of the operation was installing the the roll servo bell crank stop bracket. This bracket is important in that it prevents the push tube for the autopilot servo from going over center. If it was ever to go over center, it would lock the ailerons, which is more excitement than I care to have in an airplane. The problem is this bracket is held in place with 4 tiny screws, they are somewhere in the neighborhood of 3/32″ diameter screws, 1/8″ long with Locktite and a lock washer on them. I failed to plan ahead for this when mounting the servo to the bottom of the spar. I didn’t leave near enough room or access to get a screwdriver in there, even my right angle screw driver. I had to improvise, I needed a short reach right angle screw driver.

So i took a ratcheting screw driver insert and ground it shorter. Then I used a hemostat as my handle. I used the grease trick to hold the screw onto the screw driver tip. If you are not familiar with that, you put a dab of grease on the tip of the screw driver and it holds the screw to the driver tip. Then I carefully got the screw started. I was unable to get it to turn more than about 1/8 of a turn with each swing of the hemostat. So after each swing, I had to rotate the screw driver tip in the hemostat and go back for another 1/8 turn. Needless to say, this process took a very, very long time… and there were 4 screws. Did I say I was working overhead, sitting on the floor, in the hell hole… it took a very, very long time. But I was successful. The servo bell crank is certainly not able to go over center now. Sheesh.

Here you can see the full setup with the push pull tube installed, and everything in a flight worthy condition. While I was up there, I cleaned up the wire routing a bit as well. It has a bit to go, but at least we can tell what everything is.

While I was working on that, Greg was working on remaking the fuel distribution block mount. The one we made previously didn’t fit. The fuel distribution block mounts to the same piece of angle extrusion that mounts the oil cooler aft of the engine oil pan. When we made the first one, the oil cooler was slightly out of position. When we put everything together, the fuel distribution block wouldn’t fit in the mount. It hit the engine case. So we made a new one, moving it slightly outboard to clear the case. It took a lot of fiddling to get this one right.

The good news is, the new one works. Before final mounting, I had to safety wire the top of the fuel distribution block. We had removed the safety wire to explore mounting options. I had to do it twice, but finally got it right. Here you can see the oil cooler mounted, the fuel distribution block mounted to the oil cooler mount, and the oil pan bolts re-torqued to the specified values.

About this time, Greg had to go, and Eric came over. Eric got to work on wiring. He started by putting the connector on the aileron trim motor and the mating wires that go to the trim switch and the Garmin G3X aileron trim position sensor inputs. We are using PCI-e type connectors that are rated for high temperature.

Then he put connectors on the pressure sensors that are mounted on the sensor manifold block on the upper firewall. These are oil pressure, manifold pressure, and fuel pressure. In the following photo you can see the pressure sensor wiring and the aileron trim wiring on the right spar. The remaining wires that are coiled up are the remainder of the engine sensors and will be wired once the engine is hung. They are things like CHT, EGT, tach, etc. There are only 13 more engine sensors/indicators to wire. Note that another suggestion from James, is to move the wires to the bottom/inboard side of the pressure sensor manifold. This is to prevent snagging the wires when installing the cowl.

Of course, since we had more things wired, we had to test them. So we played with the aileron trim and watched the actuator move. Then we looked at the EFIS and saw that we were indicating manifold pressure (atmospheric pressure), oil pressure (zero), and fuel pressure (zero). In addition, we temporarily calibrated the aileron trim, and were able to see trim position on the PFD. That was very satisfying for both of us. Little victories, many little victories!

In-between helping Eric, I was working on the oil cooler exit duct. I needed to drill out the holes to the final size for mounting. Then I added nut plates around the perimeter of the aft flange. Here you can see the oil cooler exit duct mounted in place with final hardware. I think I went a little overboard on the mounting hardware, but it is rigid and adds rigidity to the baffles. 🙂

Today was a great day in the Garaggio. Lots of little things done! Can I say that I do not miss the sanding and dust, this type of work is a lot more fun.

It was another full house in the Garaggio today. Greg, Jon, and Eric were all here working on the airplane today.

Greg got a lot done on the oil cooler and fuel distribution mount. In fact, they are pretty much done with exception of having the right hardware.

Next will be making the duct that exhausts the oil cooler air our the back baffle. It’s a pretty simple piece to make, and maybe I’ll get to it tomorrow.

Jon started his day by making a mount for the autopilot roll servo. It took us quite a bit of time talking through the options to decide exactly how to mount it. Finally we decided on the bottom of the spar, which requires a mounting standoff.

Jon and my day kinda took some turns. I had planned on doing some wiring. But when Jon and I started talking about mounting the back up battery for the EFIS screen, we decided it was best to mount it to a cover over the nose gear. The cover is necessary to prevent drafty air from entering the cockpit. It also makes a nice place to mount the back up battery.

Our process was somewhat crude, but quick and functional. We fastened blocks of foam on the gear motor to create and offset and clearance around the motor. Then we “paper mâché-Ed” aluminum tape around the motor to the bulkheads and LG30s.

Then we again used a paper mâché like method and laid pre-wet out fiberglass on our form. Overlapping plies. Splicing in pieces where need be. It’s not structural except where the back up battery will mount, so there is a plywood reinforcement there. But the rest is pretty flimsy. But in reality it is an environmental cover.

By the time we did all that it was quitting time for Jon and Greg, but Eric had just arrived. So Eric and I got on to some wiring. A remaining takes from last time with Eric was to add a resistor in the landing gear indicating circuit. So he did that while I crimped some ends on power cables.

Then Eric put a circular plastic connector (CPC) on the front stick. We would have done the rear stick as well, however I screwed up when I was ordering pins. I didn’t order enough. So we need to order more.

Lastly, we permanently mounted the ground bus on the avionics shelf. We also made up a ground cable from there to the battery to complete the circuit.

That was it for today, a lot actually. We will see what tomorrow brings. But I’m looking forward to more wiring and maybe getting the switch functions working.

I didn’t get to write a blog post yesterday, because I was in the workshop until well after bed time. We had a very productive day! We also had quite a few people in the Garaggio.

Greg came over right away in the morning. He just came back from a month in Bora Bora so I gave him the tour of progress since he left. Then he got to work on finishing the oil cooler mounting brackets.

Since the fuel distribution block goes in this area too, he also started working on a mount for that. He had everything hung for a while and I didn’t remember to take a photo of it, so when there is more progress, I’ll get a photo.

Jon was also here and he did various wiring tasks. He got the big power wires terminated at the firewall. Then installed more zip tie anchors where we needed them.

Jon also got the positive side of the power to the starter solenoid. We found we didn’t have the right terminals to finish up the solenoid wiring, so that will have to wait for those to come.

In between working with Jon and Greg on those projects, I got started labeling and organizing the spaghetti bowl of wires I allowed to develop with the nose gear harness. These heat shrink tuning labels are the “cats pajamas,” as Jon would say. They really make a nice way of keeping the wiring straight.

Once the rats nest was organized, I got to work figuring out the final routing for the harness. It is running through a hole aft of the gear motor, then across the bulkhead and under the avionics shelf to the panel. I think it is going to work well.

About the time I finalized the wiring path, we had a newbie in the Garaggio. My friend Eric, who has been a pilot for years and generously provided hangar space for Dick Keyt’s bonanza during the work party earlier this year, came over after work. Eric tinkers with various projects, and I think my evil plan worked. He seems to have been bitten by the airplane building bug. In fact, he is going to Oshkosh this weekend to do the composites educational workshop. I think we have a Velocity or a Cozy in our future!

Anyways, Eric is pretty handy around wire strippers, soldiering irons, and electrical schematics. Talk about perfect timing. Between the two of us, we finished wiring the new landing gear switches, the circuit breaker, and the electrical back up system.

During testing, we did have a few head scratching moments. The gear wouldn’t stop when it hit the up or down limit. It took a while to trace what happened, and I am sure glad Eric was here because I wouldn’t have found it.

The LED gear indicator in the handle of the gear switch requires a resister in series in the ground lead. Since we didn’t put one in, we fried one of the channels on the multi colored LED and caused a short. It was the blue color which we were going to use as a transit light. This short was not allowing the limit relays to stop the motor. Once we found that and disconnected the blue channel, everything worked normally again.

We are going to install the resistor and do without a transit light. Many airplanes don’t have them, and I can’t come up with a need for it. Alright, back out to the workshop for me.